To improve pressure resistance of a main lip 12 without increasing a number of parts or complicating installation work.

The sealing device for the reciprocating shaft is provided with a metallic ring 11, the main lip 12 integrally connected to a pressure space A side and slidably and tightly brought into contact with an outer peripheral surface of a shaft 2, a backup ring 15 fitted into a fitting recess 11a formed on an inner peripheral part of the metallic ring 11 on the pressure space A side and supporting the main lip 12 from an atmosphere B side and the inner peripheral side, and a dust lip 16 integrally connected to the metallic ring 11 on an atmosphere B side and slidably and tightly brought into contact with the outer peripheral surface of the shaft 2. The main lip 12 and the dust lip 16 are continued with each other through a through hole 11b provided on the metallic ring 11. The main lip 12 and the dust lip 16 are formed at a time through the through hole 11b of the metallic ring 11 in such a state that the backup ring 15 is fitted to the fitting recess 11a of the metallic ring 11, and the main lip 12 and the dust lip 16 can be integrally formed with the metallic ring 11.